1. Field
Embodiments relate to a semiconductor device and associated methods. More particularly, embodiments relate to a semiconductor device including a vertical transistor and a method of manufacturing a semiconductor device having a vertical transistor.
2. Description of the Related Art
As semiconductor devices have become highly integrated, the size of an active region of the semiconductor device has been reduced, and thus a channel length of the semiconductor device has been considerably shortened. As for a metal oxide semiconductor (MOS) transistor, source/drain regions of the MOS transistor may strongly affect an electric field, or an electric potential in a channel region of the MOS transistor may be great when a channel length of the MOS transistor is reduced. Namely, a short channel effect of the MOS transistor may be generated as the channel length is decreased. When the short channel effect occurs in a MOS transistor, an undesirable leakage current of the transistor may increase, and a breakdown voltage of the transistor may decrease. Further, a current caused by a drain voltage may also increase. As a result, the MOS transistor may have poor electrical characteristics.
Several technologies have been developed to improve the characteristics of a semiconductor device while also reducing its size. Recently, a vertical type transistor has been developed having a pillar-shaped active region where a channel of the transistor may be formed vertically with respect to a substrate. Since the active region of the vertical type transistor may have a desired height, the vertical type transistor may have an enlarged channel length even though it has a reduced size. However, the active region of the vertical type transistor may be easily damaged and deteriorated because the active region of the vertical type transistor may be formed in a semiconductor pattern obtained by etching a semiconductor substrate. For example, the active region of the vertical type transistor may be damaged while forming the semiconductor pattern by an etching process. Thus, the vertical type transistor may have poor electrical characteristics because of a damaged and deteriorated active region.